Systematic NMR assignments of DNA exchangeable protons

Exchangeable proton information is of critical importance in the NMR struct ural studies of DNA/RNA oligomers and/or their complexes with protein. Howe ver, no systematic NMR assignment strategy about these protons has been rep orted until now, although similar studies about non-exchangeable proton ass ignment have been well established in the past decade. We now report detail ed NMR studies of a DNA duplex (d20-mer) containing the recognition site (5 '-ATGAC-3') of GCN4 basic zinc finger protein. All exchangeable and non-exc hangeable protons except H5'/H5 " protons could be assigned from a single H 2O/NOESY spectrum at 25 degrees C. The assignment strategy reported in this paper shall be useful to NMR studies of unusual DNA/RNA structures and the ir complexes with peptides/proteins.